What can deep-sea protists tell scientists about ancient protists?

Protists
Read more fromChapter Bacteria, Viruses, and Protists

In 2008, scientists studying modern deep-sea protists used their observations to extrapolate information about ancient protists. In particular, they studied the profusion of macroscopic groovelike traces in rock called trace fossils—the remnants of trails made by ancient organisms. Comparing 1.8 billion-year-old protist trace fossils to the trails of living, grape-sized protists called Gromia sphaerica, the scientists found a great similarity, concluding that many of these organisms were around in profusion much earlier than previously thought.